Frost Dates for 81122 — Bayfield, Colorado

Half of springs at Vallecito Dam, CO see their last 32°F night by May 31; only one in ten is past it by May 16, and one in ten still has one after June 14. Planting tender crops after June 4 leaves a 30% risk of a frost on them, after June 9 20%, and after June 14 10%. The 14 days between the even-odds date and the one-in-ten date is narrower than at 45% of the 110 Colorado stations behind this site's ZIP pages.

In fall the first 32°F night comes by September 26 in half of years, as early as September 14 one year in ten, and holds off past October 8 one year in ten. A hard freeze of 28°F follows 9 days later, around October 5; in spring the one-in-ten date for 28°F is June 1, 13 days before the 32°F one. The freeze-free season lasts 119 days in a typical year, shorter than at 67% of the 110 Colorado stations; it reaches 138 days one year in ten and falls short of 100 one year in ten. On average 212 nights a year drop to 32°F or below. Nights of 36°F, when frost can still settle on leaves in low, open spots, continue 11 days longer, to about June 11, and return around September 17. Severe cold of 16°F or below comes every winter, usually between November 7 and April 1.

July is the warmest month at Vallecito Dam, CO, averaging 81°F by day and 49°F at night; January is the coldest at 38°F and 7°F. A freezing night is all but certain in every month from October to May (a 90% chance or more). From July to August the chance of a 32°F night stays under 10% each month. In spring, June still brings one in 45% of years.

Warmth for growing adds up to 1,491 growing degree days a year (base 50°F), fewer than at 80% of the 110 Colorado stations. 26% of them (381) have built up by the end of June, and July adds the most, 464. Precipitation totals 25.8 inches a year, most in September (3.4") and least in June (0.9"); May to September bring 46% of it.

The nearest other station, Durango, CO, 15 miles west of Bayfield and 883 feet lower, has a last frost 10 days earlier (May 21), a first frost 6 days later (October 2), a season 15 days longer.

The first measurable snow (0.1 inch or more) in Bayfield usually arrives around November 9, and the last of the season around April 15. Those are the middle dates across the winters of 1991–2020 at Vallecito Dam, CO, 3.5 miles away: half of years saw snow earlier, half later. Every one of those winters saw snow. The last 32°F night of spring typically comes 46 days after the last snow.

ZIP 81122 is 4 miles from Vallecito Dam, CO, which stands at 7,644 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 81122 in zone 6a, the band where the coldest night of the year averaged -10 to -5°F (-23.3 to -20.6°C) over 1991–2020; a zone describes winter lows, not frost dates.